Irish has five[1] noun declensions, each with four cases (nominative,[2] vocative, genitive, dative), and singular and plural forms.[3] Noun endings are typified by broad and slender[4] consonants, and vowels; case endings are characterised by the broadening and slenderising of consonants, and the addition of suffixes.
The defining feature of each declension is the genitive singular.[5] The dative singular has distinctive features in some declensions.[6]
Plurals are categorised as weak if the genitive plural is the same as the nominative singular; and strong if the genitive plural is the same as the nominative plural. Weak plurals are formed by slenderising consonants, or adding the suffix ‑a.[7] Strong plural suffixes include ‑aí, ‑anna, ‑ta and ‑acha[8],[9] and a few nouns in -a/e with syncopation.[10] The dative plural ‑aibh[11] is non-standard, and considered archaic/dialectical.
The vocative has the same form as the nominative in the second to fifth declensions. In the first declension, it is slender in the singular and broad + a in the plural.
There are two genders in Irish, masculine and feminine. The gender of nouns in each declension is somewhat mixed, but there are clear patterns.[12]
Irish nouns undergo initial mutations.[13]
| 1st | 2nd | 3rd | 4th | 5th | ||
|---|---|---|---|---|---|---|
| Gender | m | f [14] | m [15] & f [16] | m & f [17] | f & m [18] | |
| Singular | Nom | broad | consonant | consonant | vowel ‑ín [19] consonant |
‑il, ‑in, ‑ir vowel |
| Voc | slender | - [20] | - | - | - | |
| Gen | slender | + e [21][22] | + a | - | broad -(e)ach vowel + ch, d, n | |
| Dat | - | slender [23] | - | - | slender gen | |
| Weak Plural [24] | Nom | slender + a |
+ a [7] | + a [25] | + a [26] | [27] |
| Voc | + a | + a | + a | + a | ||
| Gen | - | broad [28] | - | - | ||
| Dat | + aibh [11] | + aibh | + a | + a |
The defining feature of each declension is the genitive singular. By this definition, a few nouns defy classification, notably:
The Caighdeán lists deoch and teach as irregular, but just a little digging shows them to be second declension nouns.
Some Irish nouns belong to more than one declension. There is a distinction to be made between historical/dialectical declension variants of a particular noun, and homonyms. A good example of the latter is eas (“waterfall”) from Old Irish es, and eas (“stoat”) from Old Irish nes.
The following is not meant as an exhaustive list.
| Noun | 1st | 2nd | 3rd | 4th | 5th | Variant |
|---|---|---|---|---|---|---|
| aire | f, care | m, chief | ||||
| aireamh | m | m | ploughman | |||
| altóir | f | f | altar | |||
| araí | f, appearance | f, bridle | ||||
| beatha | f | f | life | |||
| breitheamh | m | m | judge | |||
| cistin | f | f | kitchen | |||
| cleas | m | m | m, gang | trick | ||
| cnámh | m | m | bone | |||
| cónra | f | f | coffin | |||
| cré | f | f | earth | |||
| cruicéad | m (teanglann) | m (wiki) | cricket | |||
| cú | m | m | hound | |||
| cuisle | f | f | vein | |||
| dair | f | f | oak | |||
| dún | m, str | m, wk | fort | |||
| eas | m, str, waterfall m, wk, stoat |
|||||
| eorna | f | f | barley | |||
| féicheamh | m | m | creditor | |||
| gabha | m | m | smith | |||
| méid | f, size | m, amount | ||||
| rámh | m | m (rámha) | oar | |||
| ráth | m, str, fort f, str, shoal m, wk, guarantor |
|||||
| réal | m | f | sixpenny | |||
| ros | m, linseed | m, wooded headland | ||||
| srón | f | f | nose | |||
| talamh | m | f | land | |||
| úr | m, freshness | m, heath |
Irregular:
{{ga-decl-f-irreg}}{{ga-decl-m-irreg}}{{ga-decl-m-irreg-nopl}}For declension-specific templates, see the source list on About Irish, or under the relevant appendices.
Category:Irish appendices - Nouns